An interest for an electric battery car that gets a drive energy from an electrical energy without getting the drive energy from a fossil fuel (gasoline) has been being amplified for reason such as pollution problems. Since this battery car gets the drive energy from the electrical energy, there is no exhaust gas, and there is an advantage that noise is very small.
However, the battery car emits much heat at the time of converting direct-current (DC) power that is supplied from a high-capacity battery into alternating-current (AC) power that has a variable frequency through an inverter to thus get a drive energy, the inverter should be certainly cooled or the heat emitted from the inverter should be radiated.
In general, a vehicle cooler includes a motor that generates a rotational force, an impeller that is combined with the rotor of the motor to thereby circulate air, and a radiator which is a cooler that cools or radiates heat.
At present, a fuel cell electric vehicle (FCEV) or a hybrid vehicle employs components such as a power integrated circuit (IC) chip, a metal oxide semiconductor field effect transistor (MOSFET), and an insulated gate bipolar transistor (IGBT) as a drive system for driving an electric motor, and requires that fuel cells or power components should be cooled so that they should not rise up to not less than a predetermined temperature.
In the case that fuel cells or power components rise up to more than a predetermined temperature, a vehicle speed is limited, or life of a fuel cell is shortened. Thus, a cooler which cools the fuel cells or power components is required, and a brush type of a DC motor is applied as the cooler.
In addition, a vehicle adopting a general gasoline engine drives a cooler having a motor power of 250 W in order to prevent temperature of the engine from rising up to a predetermined temperature.
The above-described brush type of the DC motor is not proper for driving an impeller of a cooler in a battery car. That is, in order to reinforce a cooling performance of a battery car, a motor power should be increased. In the case that a high power DC motor of high power, for example, 400-500 W is used, it is general that two DC motors each having a capacity of 250 W are used due to a big abrasion rate of a brush. In this case, a structural design of the battery car is complicated, and an amount of electric power consumption of a cooler is increased. In addition, in the case of a vehicle that a hydrogen fuel electric cell is mounted among battery cars, danger of fire is very high due to a flame which may occur between a hydrogen gas and a brush in a brush type DC motor.
In addition, a DC motor applied in a conventional battery car does not have a waterproof structure. Accordingly, the DC motor may be frequently influenced much because of bad weather such as snow, rain or fog.
Therefore, a BLDC motor that does not cause any problem by a brush and is not influenced because of the weather, for example, that is processed in waterproof and is not influenced by the weather circumstance should be presented so as to be applied to a cooler in the battery car.
In addition, as performance of the battery car is improved, a BLDC motor of high power required should be presented. A motor that is used for a cooler for enhancing vehicle performance is processed into a waterproofed structure so that the motor is not influenced under the weather circumstance. Further, size of the motor is minimized to thus minimize a space that occupies in a vehicle. Still further, the motor should have higher power than that of the other motors of identical size.
Meanwhile, this applicant proposed a BLCD motor of a radial core type double-rotor mode in the Korean Patent Laid-open Publication No. 2004-2349.
The BLCD motor proposed by the same applicant as that of the present invention employs a double-rotor/single-stator structure to thus enable perfect division of a stator core and maximize a winding efficiency of coil.
In addition, in order to improve an assembly of a division type stator core through the Korean Patent Laid-open Publication No. 2005-245, a stator structure and a BLCD motor using the stator structure was proposed in which a number of stator core assemblies are automatically position-set in and fixed to an annular core support, so as to be connected with divided coil.
By the way, the core holder requires for an insert molding process of integrally forming a pair of guide flanges and/or a number of coupling protrusion pairs which are necessary for automatically position-setting a division type stator core assembly in a PCB for connection of an annular band structure having a number of conduction lines and bonding pads which are necessary for mutually connecting coil on the lower surface of the core holder.
Moreover, the core holder has a structure that the stator core assembly are temporarily assembled in an annular plate formed of the PCB and the pair of the guide flanges, to thereby attain a bulk molding compound (BMC) molding. However, since the BMC molding material has a feature that mutual coherence for the PCB annular plate is weak, a stator holder enclosing the upper and lower surfaces of the PCB has a small contact area between the upper/lower portions of the PCB. Accordingly, there is a problem that coherence is weak.